By applying various heat stimuli to volunteer subjects, changes in the volume of sweating were subjected to a frequency analysis to ascertain the dynamic properties of sweating. The results revealed that, like other physiological phenomena such as brain waves and heart rates, thermal sweating is a phenomenon exhibiting fluctuations. Subjects were divided into heat acclimatized and heat non-acclimatized groups. Under a high heat environment, changes in sweating and thermal sensation were then compared between the two groups. Although no marked differences between the two groups were observed in the degree of fluctuations in sweating, differences were observed in frequency components of the specific frequency band in sweating power spectra. Changes in comfortableness differed according to acclimatization status, and the factors contributing to comfortableness for the acclimatized group were different to those for the non-acclimatized group. These findings suggest that when developing comfortable clothing for high heat environments, it is important to clarify the heat adaptability of test subjects. The results of the present study demonstrate that acclimatization to heat can be objectively assessed based on the dynamic properties of sweating, and this will prove useful for designing comfortable clothing for high heat environments.

DESCENTE SPORTS SCIENCE Vol.23/THE DESCENTE AND ISHIMOTO MEMORIAL FOUNDATION FOR THE PROMOTION SPORTS SCIENCE